A thermostat includes a wall plate unitarily molded of thermoplastic resin, a first metal plate holding a temperature sensing section, and a second metal plate holding a cam shaft. A fulcrum of a lever and a fulcrum of adjusting plate are protected by the wall plate and they are not exposed to the outside. Since both the fulcrums are not exposed to the outside, the fulcrums are free from being touched with foreign matters. This thermostat thus prevents a temperature set therein from changing.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A thermostat comprising: (a) a housing; (b) a contact; (c) a switch mechanism accommodated in the housing; (d) a temperature sensing section for converting a volume change of gas, which is expanded or compressed in response to an ambient temperature, into force that operates the switch mechanism; (e) a lever receiving the force from the temperature sensing section for rotating on a first fulcrum to turn on or off the contact; (f) an adjusting plate engaging with the lever for rotating on a second fulcrum to increase or decrease the force necessary for rotating the lever; and (g) a cam shaft including a cam that rotates the adjusting plate, wherein the housing is placed outside a supporting wall that supports the first and the second fulcrums, and includes a wall that covers the first and the second fulcrums.
2. The thermostat of claim 1 , wherein the housing includes: a wall plate, unitarily molded of thermoplastic resin, having the wall that covers the first and the second fulcrums; a first metal plate for holding the temperature sensing section; and a second metal plate for holding the cam shaft.
3. The thermostat of claim 2 , wherein the housing is generally a hexahedron, and at least four faces out of six faces are formed of the wall plate, and one face other than the four faces is formed of the first metal plate, and another one face is formed of the second metal plate, wherein the second metal plate includes the supporting wall extending along an inner face of the wall plate.
4. The thermostat of claim 3 , wherein the supporting wall includes a protruding and rising face that contacts with the inner face of the wall plate, and the supporting wall supports the first and the second fulcrums at an area other than the protruding and rising face.
5. The thermostat of claim 4 , wherein a protruding height of the first and the second fulcrums from the supporting wall is lower than a rising height of the protruding and rising face.
6. The thermostat of claim 3 further comprising: a terminal coupled to the switch mechanism and extending through a wall plate, not facing the temperature sensing section, from an inside of the housing to an outside; and an adjusting screw for finely adjusting force necessary to operate the switch mechanism; wherein the adjusting screw is disposed in the housing and placed at a position where the screw is adjustable from the metal plate holding temperature sensing section.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 16, 2003
November 16, 2004
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